The present disclosure relates to an imaging device, an endoscope, and an endoscope system.
Imaging devices such as complementary metal-oxide semiconductors (CMOS) include a light receiving unit that has a plurality of pixels; and a peripheral circuit such as a read circuit that reads signals from the light receiving unit.
Furthermore, with endoscopes, there is a need to transmit imaging signals, captured at the distal end of an insertion unit that is inserted into a body cavity, to an image processing device via a cable. If imaging signals are transmitted as analog signals without change via a cable, a pixel rate is limited, and it is difficult to improve an image quality due to an increase in the number of pixels in an imaging device. Therefore, imaging devices for endoscopes need to include an A/D conversion circuit that conducts analog/digital (A/D) conversion on imaging signals.
Japanese Laid-open Patent Publication No. 2014-17834 discloses a column-parallel AD conversion circuit where a peripheral circuit is provided in a separate chip in order to reduce a chip area. With this configuration, a chip having a pixel area and a chip having a peripheral circuit are laminated, and the chips are connected with a through-silicon via (TSV: Si through-electrode), or the like.